Triploid Grass Carp Information

Will Triploid Grass Carp Work for You?

Before deciding to stock grass carp, it's important to identify the vegetation
you want to control. Grass carp have definite food preferences. Bushy pondweed,
American pondweed, and hydrilla are preferred foods. Grass carp are not effective
for control of bulrush, filamentous algae (pond scum or moss), water primrose,
coontail, Eurasian milfoil, or cattails. If you're not sure what's growing
in your pond, try the Pond Manager
Diagnostics Tool provided by the Texas
Cooperative Extension Service.

Triploid grass carp are inexpensive
compared to most other aquatic vegetation control methods. Keep in mind,
however, that the types of plants these fish prefer may also be important
for sportfish habitat
and
waterfowl
food. Aquatic vegetation can be important in maintaining
good fish communities and providing food for other wildlife species. Stocking
grass carp may also result in alga blooms and reduced water clarity.

Triploid grass carp:

are sterile and will not reproduce.

are only distantly related to the undesirable European carp, and share
few of its habits.

feed only on plants, not on fish eggs or young fishes.

feed from the top of the plant downward; however, where all submersed vegetation
has been eliminated, the water can become turbid as hungry fish eat the
organic material out of the sediments.

go dormant during the winter and resume intensive feeding when water temperatures
reach 68°F.

live for at least 10 years and probably longer in Texas waters.

grow rapidly and may exceed 60 pounds.

are difficult to catch with conventional fishing methods.

Stocking Guidelines

The recommended stocking rate for triploid grass carp is five per acre
if the water body has 50% or less plant coverage, and 10 per acre if plant
coverage is greater than 50%. If warranted, the stocking rate can be increased
with consent of your local TPWD fisheries management biologist.

Triploid grass carp should be 10-12 inches long when stocked. Smaller carp
are likely to be eaten by other fish.

Early spring is a good time to stock. To enhance effectiveness of triploid
grass carp, overabundant vegetation should first be reduced by winter die-off,
herbicide treatment, or water-level drawdown to promote grazing on re-growth.

If the water body is overstocked, all submersed aquatic plants may be eliminated.
Removing excess fish can be difficult.

If insufficient numbers of triploid grass carp are stocked, less-favored
plants may become overabundant.

Depending on plant types, plant density, and stocking rate, it may take
several years to achieve control using triploid grass carp. Restocking, generally
every 5 to 7 years, is needed for maximum effectiveness.

Obtaining a Permit

Before stocking, water body owners, their agents, or controlling authorities
must obtain a Triploid Grass Carp Permit from the Inland Fisheries Division
of the Texas Parks and Wildlife Department. To apply for a permit:

Or, call (512) 389-4444 or 1(800) 792-1112 to request an application packet by
mail. The 800 number will get you to the main TPWD switchboard. When you
hear the recording, select 4, then 4 on the next set of options.

Once the application has been received, it will be reviewed by a District
Fisheries Management Biologist. In some cases, a TPWD staff member will contact
you or make an on-site visit to ensure the fish will not escape into public
waters. Allow 4 to 5 weeks for the entire permit process. Acceptance
of your application is not guaranteed. Stocking of triploid grass carp is not allowed
in some environmentally sensitive areas where threatened, endangered, or unique
species occur.

After you receive an approved permit, triploid grass carp must be purchased
from a commercial fish farmer who holds an Exotic Species Permit authorizing
possession of triploid grass carp. A list of permitted fish farmers will be
provided with your approved permit.

If you need additional fish, it will be necessary to apply for a new permit.

Preventing Escape

Triploid grass carp readily seek flowing water and often escape before controlling
nuisance aquatic plants. Escapement of the stocked fish can reduce or eliminate
their potential for plant control within targeted areas, and can threaten beneficial
plants outside of targeted areas. Therefore, emigration barriers
are required for many, and recommended for most, water bodies being stocked
with triploid grass carp. Ensuring that triploid grass carp remain where they
are stocked makes economic sense for the water body owner and helps protect
beneficial aquatic vegetation
in our public waters. In cases where emigration cannot be prevented, chemical
or mechanical control of aquatic plants is recommended.

Figure 1 - Spillway Barrier

With few exceptions, the best screening device for nearly all outlet types is
the horizontal parallel steel-bar design. The orientation of the bars allows
unrestricted passage of small debris, thereby minimizing maintenance, clogging,
and flooding concerns. Bar thickness of ¼- to ½- inch is preferred.
Round bar stock will facilitate debris passage. For a spillway barrier (Figure
1), the horizontal bars are attached to vertical support posts (minimum ¾-inch
diameter) spaced 4 feet apart. Horizontal bars should be spaced 2 inches apart.
The barrier should span the entire spillway. Since triploid grass carp are excellent
jumpers, barrier height should extend 2 feet above the normal high water level.

Figure 2 - Drainage Pipe Cap

For capping a drainage pipe (Figure 2), a similar bar design should be
used. Extending the bars 4-5 feet above the overflow pipe allows water
to rise over debris and begin flowing again should the screen become
clogged.

Welded wire and chicken wire are not effective as barrier materials.
These types of materials readily clog with debris and the force of
even a small amount of water can destroy the barrier. Clogged barriers
may threaten the integrity of dams.